#459: data_validator.py, minor docblock changes
#459: data_validator.py, add dockblock for 'prelearning_data_validation'
#459: data_validator.py, add method header
#654: data_validator.py, add validation logic
#654: data_validator.py, call correct method for jsonschema validation
#654: data_validator.py, correct method names
Merge pull request #670 from jeff1evesque/python_data_validator

#654: Add jsonschema for 'data_validation' method